This invention relates generally to scanning spectrometers and more particularly concerns a spectrometer which works on the principle of varying angles of incidence of light on an interference filter or diffraction means to permit analysis of the spectrum of that light.
Spectrometers work by isolating a certain input flux, dispersing that flux into its constituent wave length parts, and then focusing the resultant "picture" or spectrum onto a recording detector such as a photographic plate or other elctromagnetic radiation detector or sensor. In order to analyze or make measurements on the output spectrum, it is necessary to be able to identify each spectral feature either as a function of time as that feature passes along the recording sensor or as a function of wave length. In standard spectroscopes, such as the Czerney-Turner spectroscope, the dispersion means consists of a difraction grating which is movable in relation to the body of the spectrometer to enable a scan of the spectrum of the light being analyzed.
There are advantages to spectrometers which permit wave length scanning with minimal or no movement of the dispersing element. In such a case, the dispersing element can be more closely controlled since it does not have to move rapidly, and the wave length scan or differentiation, dI/d .lambda., can be made independent of time and hence a potential source of signal-to-noise confusion is eliminated (here I is the intensity or irradiance value).
Nevertheless such instruments still have drawbacks. The scans must still be accomplished by mechanical devices which can easily become misaligned and which can be somewhat awkward to handle compared to the rest of the spectrometer. Further, the motion required can occasionally disturb the alignment of the main dispersing element in the instrument, making the output data meaningless.
Accordingly it is an object of the present invention to eliminate or minimize the difficulties presented by such systems by providing a spectroscope which enables a scan without movement of the dispersion element. It is a further object of the invention to provide such spectroscope which may enable the carrying out of a scan electronic means alone and the requirement of no moving parts.